Porous carbon-carbon composite and process for producing the same

Abstract

A porous isotropic carbon-carbon composite having a porosity of 25 to 85% and substantially isotropic mechanical strength, and containing 60% by weight or more of aggregate particles having an aspect ratio of 10 or smaller and reinforced in one direction with carbon fiber is provided.

What is claimed is: 
     
       1. A porous isotropic carbon-carbon composite characterized by having a porosity of 25 to 65%, having substantially isotropic mechanical strength, and containing 60% by weight or more of aggregate particles, said aggregate particles having an aspect ratio of 10 or less and being reinforced unidirectionally by carbon fibers. 
     
     
       2. A process for producing a porous isotropic carbon-carbon composite, comprising impregnating a reinforcement material of a pitch fiber having been subjected to infusiblization treatment or a pitch-based carbonaceous fiber carbonized at a temperature of 2200° C. or lower, said reinforcement material being arranged unidirectionally, with a liquid carbonizable material, carbonizing the impregnated reinforcement material at a temperature of 2200° C. or lower, grinding the resulting unidirectionally reinforced carbon-carbon composite so that the particle size is 5-325 mesh and the aspect ratio is 10 or smaller, blending 60% to 90% by weight of the resulting ground composite as aggregate particles with 40% to 10% by weight of a pitch having a softening point of 220° C. or higher, pressure molding the blend at a temperature in the range of 5° to 100° C lower than the softening point of said pitch and at a pressure in the range of 80 to 400 kg/cm 2 , and carbonizing the resulting molding to give a product having a porosity of 25 to 65% and isotropic mechanical strength. 
     
     
       3. A process for producing a porous isotropic carbon-carbon composite, comprising impregnating a reinforcement material of pitch fiber having been subjected to infusiblization treatment or a pitch-based carbonaceous fiber carbonized at a temperature of 2200° C. or lower, said reinforcement material being arranged unidirectionally with a liquid carbonizable material, carbonizing the impregnated reinforcement material at a temperature of 2200° C. or lower, grinding the resulting unidirectionally reinforced carbon-carbon composite so that the particle size is 5-325 mesh and the aspect ratio is 10 or smaller, blending 60% to 90% by weight of the resulting ground composite as aggregate particles with 40% to 10% by weight of a pitch having a softening of 220° C. or highter, pressure molding said blend at a temperature in the range of 5 to 100° C. lower than the softening point of said pitch and at a pressure in the range of 80 to 400 kg/cm 2 , and carbonizing and graphitizing the resulting molding to give a product having a porosity of 25 to 65% and isotropic mechanical strength. 
     
     
       4. A process according to claim 2 or 3 in which a liquid carbonizable material used to impregnate reinforcement material is a pitch.